1. Field of the Invention
The present invention relates to a fluid supply valve attachment device in which a fluid supply valve is fixedly attached to a tank that has a fluid tank chamber which stores fluid in a pressurized state.
2. Description of the Related Art
Japanese Patent Application Publication No. 2005-140195 (JP-A-2005-140195) discloses a fluid supply valve attachment device in which a fluid supply valve is fixedly attached to a tank that has a tank chamber. FIG. 9 schematically shows the fluid supply valve attachment device. As shown in FIG. 9, the fluid supply valve attachment device has a tank 3 that has a tank chamber 30, a fixing member 1 that is fixed to the tank 3, and a fluid supply valve 4 that is inserted in the fixing member 1. The tank 3 has a mounting hole 32, a first inner peripheral surface 33 in which the mounting hole 32 is formed, and the tank chamber 30 that communicates with the mounting hole 32. The fixing member 1 is fixed to the mounting hole 32 of the tank 3 in a fit state and has a first outer peripheral surface 105 that faces the first inner peripheral surface 33 of the mounting hole 32, a recessed fitting section 17 that is disposed inside in the radial direction of the first outer peripheral surface 105 to open toward the tank chamber 30, and a second inner peripheral surface 19 that forms the recessed fitting section 17. The fluid supply valve 4 is inserted in the recessed fitting section 17 of the fixing member 1 to be mounted thereto and has a second outer peripheral surface 403 that faces the second inner peripheral surface 19 of the recessed fitting section 17. A first seal member 14 in a ring shape is provided between the first inner peripheral surface 33 of the tank 3 and the first outer peripheral surface 105 of the fixing member 1. The first seal member 14 seals a space between the first inner peripheral surface 33 of the tank 3 and the first outer peripheral surface 105 of the fixing member 1. Further, as shown in FIG. 9, a second seal member 65 in a ring shape is provided between the second inner peripheral surface 19 of the fixing member 1 and the second outer peripheral surface 403 of the fluid supply valve 4. The second seal member 65 seals a space between the second inner peripheral surface 19 of the fixing member 1 and the second outer peripheral surface 403 of the fluid supply valve 4 and has a ring shape with a diameter smaller than the first seal member 14. The first seal member 14 and the second seal member 65 prevent hydrogen that is stored in the tank chamber 30 of the tank 3 from leaking.
As shown in FIG. 9, in the device described above, the distance between the cross-sectional center of the first seal member 14 and the cross-sectional center of the second seal member 65 is denoted as L2. Even when the fluid supply valve 4 is closed, since the gas in the tank chamber 30 of the tank 3 is at high pressure, the gas inevitably enters a gap 201 between the first inner peripheral surface 33 of the mounting hole 32 of the tank 3 and the first outer peripheral surface 105 of the fixing member 1. In other words, it is considered that high-pressure gas enters an area WA (area indicated by Δ (triangle) in the gap 201) of the gap 201 that is located more adjacent to the tank chamber 30 than the first seal member 14. Therefore, in the area WA, pressure Fi (see FIG. 9) due to high-pressure gas is applied to the fixing member 1 in the radially inward direction.
However, it is not easy even for gas to move over the first seal member 14 in the direction D1. Therefore, it is considered that the pressure in an area VA (area indicated by ∘ (circle) in the gap 201) of the gap 201 that is more away in the direction D1 from the tank chamber 30 than the first seal member 14 is substantially at the atmospheric pressure.
Further, the gas (hydrogen gas) at high pressure in the tank chamber 30 of the tank 3 also inevitably enters a gap 204 between the second inner peripheral surface 19 and the second outer peripheral surface 403. In this case, it is considered that the high-pressure gas enters an area WB (area indicated by x (cross) in the gap 204) of the gap 204 that is located more adjacent to the tank chamber 30 than the second seal member 65. Therefore, in the area WB, pressure Fp (see FIG. 9) due to high-pressure gas is applied to the fixing member 1 in the radially outward direction.
However, it is not easy even for gas to move over the second seal member 65 in the direction D1. Therefore, it is considered that the pressure in an area VB (area indicated by ● (filled circle) in the gap 204) of the gap 204 that is more away in the direction D1 from the tank chamber 30 than the second seal member 65 is closer to the atmospheric pressure than pressure in the area WB. In this case, the directions of the pressures Fp and Fi are opposite from each other, and thus both of the forces cancel each other.
However, as it can be understood from FIG. 9, if the distance L2 is provided in a manner such that the first seal member 14 and the second seal member 65 are remote from each other in the extending direction D2 in which the recessed fitting section 17 extends, it increases an area on which only the force in the direction Fp (radially outward direction) is applied to a first section 11 of the fixing member 1. In other words, only the force in the direction Fp that is oriented in the radially outward direction is applied in the distance L2. Therefore, this increases unnecessary load that the first section 11 of the fixing member 1 is deformed in the radially outward direction. In this case, since the pressure of the gas in the tank chamber 30 is high as described above, the load is large. Therefore, the first section 11 of the fixing member 1 may be deformed in the radially outward direction and may fatigue due to the deformation. Further, deformation of the first section 11 of the fixing member 1 may apply unexpected load to the first seal member 14. Particularly, in the case that the fixing member 1 is formed of an aluminum alloy, stainless steel, or the like that is relatively flexible metal to prevent hydrogen embrittlement, the influence by the load is large.